The invention relates to RF signal combiners and dividers, and more particularly to RF signal combiners and dividers for use with solid state power amplifiers.
The development of solid-state power amplifiers for RF transmitters has created challenges to designers not present in previous tube designs. One major problem with solid-state designs is their limited power handling capability. While high power devices have been developed, they are generally quite expensive and thus are not desirable for designs where cost is a significant factor.
One strategy for solving this dilemma has been to divide the signal to be amplified into several components and direct them to a like number of smaller solid-state power amplifiers. The outputs of the power amplifiers are then combined to provide an output signal level which is comparable to or higher than the output signal which could have been obtained from a single high power solid-state power amplifier.
This divide-and-conquer strategy has its own drawbacks, however. The primary drawback is that signal dividers and combiners have usually been implemented using conventional wound transformers and lumped inductive and capacitive components to achieve the required impedance matching. Such components are inherently narrow-banded and are thus impractical for applications where wide bandwidths are required. Modern solid-state power amplifiers are generally broad-banded, and conventional narrow-banded signal splitters and combiners would severely limit their utility.
It is therefore an object of the present invention to reduce the cost of solid-state power amplifiers which produce high power outputs.
It is another object of the present invention to provide a signal splitter/combiner which is broad-banded.
It is a further object of the present invention to provide a signal splitter/combiner which is compatible with modern solid-state amplifier designs.
It is still another object of the present invention to provide a signal splitter which provides equal output signal levels for maximum power amplifier efficiency.
It is still a further object of the present invention to provide a signal combiner having high power handling capability.
It is yet another object of the present invention to provide a signal splitter/combiner having zero or 180 degrees of phase shift.
It is yet a further object of the present invention to provide a signal splitter/combiner having low insertion losses.
It is still an additional object of the present invention to provide a signal combiner having a high degree of isolation between the input ports.
It is still an additional object of the present invention to provide a signal splitter/combiner having low input and output voltage standing wave ratios.